It is well known that back pain and back disorders afflict a major segment of the population. There are numerous causes for these problems such as bad posture, poor sitting habits, or poor physical condition, resulting in distortion of the natural elongated S-shape of the spinal column. A well constructed and properly adjusted backrest tends to restore the spinal S-curve to its proper configuration, thus relieving or avoiding the uneven pressures on discs and vertebrae which cause undue pain and fatigue.
In addition to the prior Morgenstern et al. patents mentioned above, the following prior art patents were noted as pertinent to the backrest art:
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